CD14+ human monocytes exhibit high phagocytic activity and produce cytokines and reactive oxygen species upon activation of TLR2/4 in response to a wide range of microbial cues, whereas CD14dim monocytes have a weaker phagocytic ability and mainly produce cytokines in response to TLR7/8 ligands during viral infections.[51] Given our findings that surgery increases the number of Ly6Chi monocytes and that elimination of Gr1+ monocytes is neuroprotective, it is likely that Ly6Chi (CD14+) monocytes are involved in mediating the cerebral effects associated with PND. This evidence concerns the gene TLR2 and viral infectious disease.